Researchers with NASA's Operation IceBridge have completed another successful Arctic field campaign. On May 23, NASA's P-3 research aircraft left Thule Air Base, Greenland, and returned to Wallops Flight Facility in Virginia ...

A new study has found that the Antarctic Ice Sheet began melting about 5,000 years earlier than previously thought coming out of the last ice age – and that shrinkage of the vast ice sheet accelerated during eight distinct ...

Reports that a portion of the West Antarctic Ice Sheet has begun to irretrievably collapse, threatening a 4-foot rise in sea levels over the next couple of centuries, surged through the news media last week. But many are ...

A newly-discovered source of oceanic bioavailable iron could have a major impact our understanding of marine food chains and global warming. A UK team has discovered that summer meltwaters from ice sheets are rich in iron, ...

Greenland's icy reaches are far more vulnerable to warm ocean waters from climate change than had been thought, according to new research by UC Irvine and NASA glaciologists. The work, published today in Nature Geoscience, ...

The new finding that the eventual loss of a major section of West Antarctica's ice sheet "appears unstoppable" was not completely unexpected by scientists who study this area. The study, led by glaciologist Eric Rignot at ...

A rapidly melting section of the West Antarctic Ice Sheet appears to be in irreversible decline, with nothing to stop the entire glacial basin from disappearing into the sea, according to researchers at the University of ...

Ice sheet

An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² (20,000 mile²). The only current ice sheets are in Antarctica and Greenland; during the last glacial period at Last Glacial Maximum (LGM) the Laurentide ice sheet covered much of Canada and North America, the Weichselian ice sheet covered northern Europe and the Patagonian Ice Sheet covered southern South America.

Ice sheets are bigger than ice shelves or glaciers. Masses of ice covering less than 50,000 km2 are termed an ice cap. An ice cap will typically feed a series of glaciers around its periphery.

Although the surface is cold, the base of an ice sheet is generally warmer due to geothermal heat. In places, melting occurs and the melt-water lubricates the ice sheet so that it flows more rapidly. This process produces fast-flowing channels in the ice sheet — these are ice streams.

The present-day polar ice sheets are relatively young in geological terms. The Antarctic Ice Sheet first formed as a small ice cap (maybe several) in the early Oligocene, but retreating and advancing many times until the Pliocene, when it came to occupy almost all of Antarctica. The Greenland ice sheet did not develop at all until the late Pliocene, but apparently developed very rapidly with the first continental glaciation. This had the unusual effect of allowing fossils of plants that once grew on present-day Greenland to be much better preserved than with the slowly forming Antarctic ice sheet.